Integrally molded polymer hitch step

ABSTRACT

A trailer hitch step, integrally molded of a polymer compound, is capable of accepting a predetermined off-axis vertical load without an objectionable degree of torsional displacement, while also being capable of resiliently absorbing energy from rear impacts.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 14/070,275 filed Nov. 1, 2013, which is in turn acontinuation-in-part of U.S. patent application Ser. No. 13/953,121filed Jul. 29, 2013. Both of the foregoing pending patent applicationsare owned by a common assignee hereof and the disclosure and drawings ofboth of them are fully incorporated by reference herein.

BACKGROUND OF THE INVENTION

Pickup trucks, sport utility vehicles (SUVs), vans and mini-vans oftenhave trailer hitch receivers that mount to the frame of the vehicle. Acommon type of trailer hitch receiver has a rearward-facing opening thataccepts ball mounts, bike racks, cargo carriers and other hitch mountedaccessories. One accessory often attached to the hitch is a platform orstep attachment, also known as a hitch step. By providing a raisedplatform, the platform or step attachment makes the bed of the truck orSUV more accessible to the user. However, because the platform or stepattachment extends rearwardly past the bumper, it will be the point offirst impact for many rear end collisions.

Thus a need exists for a hitch step that absorbs force from the impactof a rear end collision.

Prior hitch steps have been formed of metal, usually steel. This isbecause the hitch step, to be commercially acceptable, has to withstandthe application of the weight of an adult at an off-axis positionwithout unacceptable torsional or cantilever deformation. Prior hitchsteps therefore add considerable weight to the vehicle and their abilityto absorb, rather than transmit, impacts from the rear of the vehicle islimited.

SUMMARY OF THE INVENTION

According to one aspect of the invention, a hitch step for insertioninto a vehicle hitch receiver is integrally molded from a polymericmaterial. A substantially hollow step body of the hitch step has atleast one vertically and transversely oriented internal support memberand presents an upper surface for receiving a vertical load of a foot ofa user. At least one external face of the step body, parallel to thehitch receiver axis, is open. The transverse support member has athickness which is many times less than the depth of the step body andextends for at least a substantial portion of the step body's height.

A substantially hollow tongue of the hitch step is sized to be receivedinto the hitch step receiver and extends axially forwardly from the stepbody. The width of the tongue is many times less than a width of thestep body. The tongue has a throat region adjoining the step body and aforward region extending forwardly from the throat region. The throatregion has at least one external face which is parallel to the axis andwhich is open. Vertically disposed reinforcing plates of the throatregion extend from the open face vertically to either a horizontal panelof the throat region or to an opposed external face of the throatregion. The forward region of the tongue has at least one external openface parallel to the axis and a vertical plate disposed in parallel tothe axis. The thickness, in a transverse direction, of the verticalplate is many times less than the width of the tongue. At least onetrailer hitch pin hole is formed to transversely extend through thevertical plate.

According to another aspect of the invention, a hitch step is integrallymolded of a polymer compound and has a step body and a tongue. The stepbody is joined to a rear end of the tongue. The height and width of thetongue are preselected so as to be closely slidably received into avehicle hitch receiver. The width of the body is many times that of thetongue. The tongue includes a throat region formed adjacent to the bodyand a forward region extending forwardly from the throat region. Atleast one hitch pin hole extends transversely through the forwardregion. The throat region has at least one open external face parallelto the receiver axis. A volume of the throat region extends verticallyfrom the open face, and extends either to an opposed throat region faceor to a panel. Reinforcing plates of the throat region extend verticallyfrom the open face and divide all of the throat region volume intosubstantially triangularly prismatic cells. In use, the step body issolely supported by the tongue. The reinforcing plates of the throatregion are so disposed that they will resist torque around the axiscaused by the weight of a user imposed on a step body top surface at atransversely off-axis location.

According to another aspect of the invention, the hitch step may beintegrally injection-molded from a relatively stiff thermoplasticelastomer (TPE). The hitch step has a step body and a tongue joined tothe step body. The tongue is sized to be slidably received into avehicle hitch receiver and in use provides the sole support for the stepbody, which has a width which is many times greater than the width ofthe tongue. When a load of 250 pounds is placed on the top surface ofthe step body at a location transversely displaced from the axis byabout four inches, and at room temperature, the step body will deflectin a plane perpendicular to the axis by no more than ten degrees, andwill resume its initial position after the weight is removed.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects of the invention and their advantages can be discernedin the following detailed description, in which like characters denotelike parts and in which:

FIG. 1 is an isometric view of one embodiment of an injection-moldedhitch step according to the invention;

FIG. 2 is a bottom view of the hitch step shown in FIG. 1;

FIG. 3 is a side view of the hitch step shown in FIG. 1;

FIG. 4 is a side sectional view of the hitch step shown in FIG. 1;

FIG. 5 is a side sectional view similar to that shown in FIG. 4, but ofa second embodiment including a metal reinforcing member;

FIG. 6 is a bottom sectional view taken substantially along line 6-6 ofFIG. 5;

FIG. 7 is a bottom view of a hitch step according to a third embodimentof the invention, in which all internal reinforcing members of the hitchstep body have been removed;

FIG. 8 is an isometric view of a fourth embodiment of the invention, inwhich the hitch step body is formed by a lattice of internal rectilinearsupport members but with no external closed faces of the support body;

FIG. 9 is an isometric view of a fifth embodiment of the invention, inwhich the hitch step body is formed by a series of vertically extendingcylindrical tubes without either a top or a bottom closed face;

FIG. 10 is a bottom view of a sixth embodiment of the invention, inwhich the step body and tongue have been integrally injection-molded ofa thermoplastic elastomer, showing elastic displacement of the step bodyfrom an off-axis rear impact;

FIG. 11 is an isometric view of a seventh embodiment of the invention,which includes an overmolded friction pad on a top surface of the stepbody;

FIG. 12 is an isometric view of an eighth embodiment of the invention,showing varying step body height and an alternative tongue construction;

FIG. 13 is a top sectional detail taken substantially along line 13-13of FIG. 12;

FIG. 14 is bottom view of a ninth embodiment of the invention, showingan alternative reinforcing rib or support member structure;

FIG. 15 is an exploded bottom view of a tenth embodiment of theinvention, illustrating an injection-molded hitch step and reinforcinginsert;

FIG. 16 is a bottom view of an eleventh embodiment of the invention,illustrating additional reinforcing ribs;

FIG. 17 is a side view of a hitch step with an alternative receivertongue structure; and

FIG. 18 is an enlarged perspective view of the alternative receivertongue structure shown in FIG. 17.

DETAILED DESCRIPTION

The present invention provides an injection-molded plastic hitch stepfor insertion into a receiver type hitch on a vehicle. In the embodimentshown in FIG. 1, a step platform or hitch step, indicated generally at100, includes a step body 102 and a receiver tongue or post 104. Theillustrated embodiment of the receiver tongue 104 has a squarecross-section that is so dimensioned that it will closely fit into apopular size of hitch receiver (nominally two inches, but typicallyslightly larger); in one embodiment, the width and height of the tongue104 are 2.00 inches, with stripes or “crush areas” which protrudeslightly from the general surface and which therefore slightly increasethe contact dimensions to achieve a close fit with the receiver. Thereceiver tongue 104 can be 6.4 inches long from its forward end to itsjunction with the step body. The tongue 104 can be dimensioned otherwiseto fit other hitch receiver types.

The hitch step 100 preferably is formed from a polymeric compound byinjection molding, reaction injection molding, or compression molding.The polymeric compound may be thermoplastic or thermosetting. Inalternative embodiments, the hitch step 100 could be machined from ahard plastic or a metal such as aluminum. In the embodiments illustratedin FIGS. 1-4, 7-10, 12-14 and 16-18, however, all of hitch step 100 isintegrally formed of a thermoplastic or thermosetting polymer compoundin a single-shot mold and has no steel, metal or other structuralreinforcements. Preferably the step 100 is injection-molded from athermoplastic compound. It is particularly preferred that the compoundused be a stiff thermoplastic elastomer (TPE) of a high flexuralmodulus, hardness and compression strength. Polyester-polyether blockcopolymer TPE compounds such as DuPont Hytrel® 7246 have been found toexhibit good elastic memory and resistance to impact, cantilever andtorsional forces. Key properties of Hytrel® 7246 appear in the followingtable:

TABLE I Property Test Method Value Flexural Modulus ISO 178 −40 C. 2350MPa  23 C.  550 MPa 100 C.  200 MPa Hardness, Shore D ISO 868  15 s 68Maximum 72 Coefficient of Friction ASTM D 1894 0.23 static, 0.16 dynamicASTM D 3702 0.90 dynamicAlternatively, other thermoplastic polyester elastomer compounds, ormore broadly other TPEs, with approximately the same physical properties(particularly flexural modulus) could be used, such as one or more ofthe TPE's sold under the mark Riteflex® and available from Celanese.As used herein, a “thermoplastic elastomer” or “TPE” includes anythermoplastic polymer compound which, in its molten state, can be usedto create a hitch step by molding, and which, in its cooled, solidifiedstate, exhibits a substantial amount of elasticity. While a TPE ispreferred, a thermoplastic polyolefin (TPO) such as a polypropylene orpolyethylene, or another thermoplastic polymer such as acrylonitrilebutadiene styrene (ABS), could be used instead.

In the embodiment shown in FIG. 1, the step body 102 has a rear panel106 with an exterior surface 108. The rear panel 106 is nearlyperpendicular or at right angles to a longitudinal or fore-and-aft axisX, which in use will align with the axis of the hitch receiver. Rearpanel 106 may be planar or may have a slightly convex curve such as acurve with a 400 inch radius. The rear panel 106 has a bottom edge 110and a top edge 112. The step body 102 may have a right exterior sidepanel 114 which is substantially parallel with the longitudinal axis Xand which joins the rear panel 106.

While rear panel 106 is nearly perpendicular to axis X, preferably it isnot completely so, but is slightly forwardly sloped from its bottom edge110 to the top edge 112. The slope can be chosen from the range of ½ to3 degrees, and is about 3 degrees in the illustrated embodiment. In thisillustrated embodiment, body 102 has an open bottom (as will beexplained below), and this slope creates a draft that is advantageousfor mold release. Side panel 114 and opposed side panel 210 (see FIG. 2)likewise are slightly sloped toward axis X from their bottom edges 115to their top edges 117, and in this illustrated embodiment this slope isabout 3 degrees. The slope otherwise can be selected from the range of ½to 3 degrees. The top edges 112, 117 of respective exterior panels 106,114 may be radiused as shown.

The width or transverse dimension of rear panel 106, and of step body102 in general, can be about 12 inches, while a depth (in parallel toaxis X) of panels 114 and 210, and of step body 102 in general, can beabout 4 inches. Panels 106, 114, and 210 can be about 2.5 inches high;in this illustrated embodiment this vertical height is somewhat morethan the height of tongue 104 and permits a greater transverse sectionalarea of the reinforcing plates or members (described below) to betterresist an off-axis vertical load. More generally it is preferred thatthe step body 102 be at least as tall as the tongue 104. The bendingmoment of the vertical support members internal to step body 102(described below) is proportional to the cube of their height, and thusa tall step body is far stronger and more resistant to torsion than athin one, for any given material; specifying a step body 102 to be atleast as tall as tongue 104 permits the use of a moldable polymer inplace of steel.

The top of the step body 102 may have a top exterior panel 116 which maybe joined to the rear panel 106 and the side panels 114, 210. The toppanel 116 is substantially horizontal and may have an exterior or uppersurface 118. The vertical location of top panel 116 may be offset fromthe vertical location of top panel 120 of tongue 104 to provide furtherstiffness of the hitch step body 102 around axis X. Disposing top panel120 above tongue 104, instead of disposing a bottom of body 102 belowtongue 104, also interposes more of the step body 102 between thevehicle bumper (usually positioned above the hitch receiver) and anyobject that it would otherwise impact.

A series of elongate longitudinal indentations or treads 128 andelongate transverse indentations or treads 130 may be formed on theexterior surface 118, and may take a concave form as shown. In theillustrated embodiment, the longitudinal treads 128 are formed to be inparallel with each other and are regularly spaced apart. Similarly,transverse treads 130 are formed to be in parallel with each other andare regularly spaced apart. The longitudinal and transverse indentations128, 130 provide traction to the user when using the step; however, thenumber and placement of the indentations can vary from the illustratedembodiment. The illustrated indentations or treads 128, 130 are straightin the direction of their elongation, and add a modicum of stiffness inlongitudinal (fore and aft) and transverse (side to side) directions.They are also useful in hiding mold or sink marks caused by the moldingof vertical support members positioned immediately beneath some of them,as will be described below. Further, the local thickness of the partincreases at the junctions of those vertical support members and the toppanel 120. Making a scallop cut in the top surface of panel 120 locallydecreases this thickness and thus tends to mitigate problems otherwisecaused by the thickening of the walls, including slower cooling, highercrystallinity and differential shrinkage.

The step body 102 is attached to a forwardly extending receiver post,tang or tongue 104 which will be discussed in further detail below, andin the illustrated embodiment step body 102 and tongue 104 areintegrally injection-molded as a single unit. In this illustratedembodiment, top panel 120 is formed of a TPE, such as Hytrel® 7246, andmay have a coefficient of friction that is significantly greater than ametal, or even of other plastics such as ABS, polyethylene orpolypropylene. According to testing done according to ASTM D3702,Hytrel® 7246 exhibits a dynamic coefficient of friction of 0.90. This isfar “stickier” than the dynamic coefficients of friction obtained bythis test method of alternative polymers: high density polyethylene(HDPE), 0.28; ultrahigh molecular weight polyethylene (UHMW-PE), 0.12;polypropylene monomer, 0.26; ABS, 0.35. Thus, the selection of a TPE asthe polymer compound confers the additional advantage of providing amore slip-resistant top surface 118, without the necessity of adding asofter or more rubbery top layer.

As seen in the embodiment illustrated in FIG. 2, the step body 102 issubstantially hollow. The rear panel 106 has an interior side 202 andmay join a left exterior side panel 210 of step body 102. The leftexterior side panel 210 is substantially parallel to axis X and istransversely spaced from the right exterior side panel 114. The leftexterior side panel 210 may extend vertically to join the top panel 116.In the illustrated embodiment left exterior side panel 210 is a mirrorimage of right exterior side panel 114, and preferably is slightlyinwardly sloped from its bottom edge 115 to its top edge 117, as by aslope selected from the range of ½ to 3 degrees.

Many of the embodiments of the present invention will have at least oneinternal, vertically disposed support member within step body 102. Thissupport member, plate or wall has a thickness which is many timessmaller, and usually an order of magnitude smaller, than any overalldimension of step body 102. Particularly as using injection molding tofabricate step 100, the external walls and reinforcing members of thestep 100 should be made as thin as possible, to save material anddecrease cycle times. The step 100 preferably is built to a nominal wallthickness that is used throughout for the external walls; internalreinforcing members can be either 50%-75% as thick as this nominal wallthickness or, in selected areas, 100% of it. With the preferred polymercompound, a nominal wall thickness of 0.20″ can be used; the nominalwall thickness can be chosen otherwise, such as 0.25″, as an inversefunction of the strength of the material. More uniformity in wallthickness promotes more uniform cooling and tends to mitigate problemsassociated with crystallization and nonuniform shrinkage.

In the embodiment illustrated in FIGS. 2-6, at least one transverseinternal reinforcing or support member 204 is disposed forwardly of therear exterior panel 106. The support member 204 may take the form of avertically extending wall, plate or panel and has a rear surface 206.Member 204 may extend between and be joined to the right side panel 114,the left side panel 210, and the top panel 116. In the illustratedembodiment, vertical support member 204 is straight, extends for theentire transverse dimension of step body 102, and is orthogonal to axisX, and this disposition optimizes support member 204 to sustain off-axisvertical loading of step body 102.

Some embodiments may include additional transverse support members orplates 216 such as the two additional transverse members 216 shown inFIG. 2. In this illustrated embodiment, the additional transversemembers 216 are disposed substantially at right angles to axis X and areforwardly spaced from the first transverse member 204 and spaced fromeach other, preferably by at least their thickness. The additionaltransverse members 216 may be straight and may extend between the rightexterior side panel 114 and the left exterior side panel 210.

This illustrated embodiment further has longitudinally aligned, internalsupport members 214 which may be walls, panels or plates, and may extendfrom the transverse member 204 to the forward external body panel 212.The longitudinally aligned support members 214 are spaced from eachother and are at substantially right angles to the transverse members204, 216; however the number of additional transverse members 216 andspacing of the additional transverse members 216 may vary from what isshown in the illustrated embodiment of FIG. 2. Longitudinal supportmembers 214 extend vertically to the bottom surface of top panel 116 andresist any torsion along axis X from throat region 232 when a verticalload is imposed on step body 102.

In this illustrated embodiment, more than one oblique cross member 208extends from the interior side 202 of the exterior rear panel 106 to therear surface 206 of the transverse member 204. In this illustratedembodiment eight oblique cross members 208 are shown, but otherembodiments may have more or fewer than these. Each of the oblique crossmembers 208 is disposed at an angle between zero and ninety degreesexclusive from axis X; in the illustrated embodiment the angle isapproximately forty-five degrees. Additionally, in the illustratedembodiment half of the oblique cross members 208 are on eithertransverse side of axis X, with their angular dispositions selected suchthat members 208 are bilaterally symmetrical about axis X. The obliquecross members 208 are adapted to collapse in a forward direction, suchthat their angle to axis X increases, upon impact being applied to theexterior surface 108 of the rear panel 106. Therefore, in the event of arear end collision, the collapsing oblique cross members 208 will absorbat least some of the force of the impact. Cross members 208 may have athickness which is several times less than their length and may take theform of panels or plates, as shown. The members 208 can have a thicknesswhich is 50-75% of the nominal wall thickness adopted for the step 100.

Exterior panels 106, 114, 116, 210 and 212, as well as the exteriorpanels of the tongue 104, have a nominal wall thickness which isselected as a function of the off-axis vertical load which hitch step100 is meant to sustain, the spacing apart and presence of any internalvertical support members, the overall dimensions of hitch step 100, andthe composition of the polymer compound used to mold the hitch step 100.In the embodiments illustrated in FIGS. 1-4 and 16-18, the nominal wallthickness has been selected to be about 0.2 inches. This wall thicknessvaries with draft or tapering. In some embodiments, the thickness of theinternal vertical support members 204, 214, 216, 208, and of theinternal support members (described below) of tongue 104, can beselected to be about 50-75% of the preselected nominal wall thickness.In other embodiments the thickness of the internal vertical supportmember(s), or selected ones of them, can approach the preselectednominal wall thickness, or even locally exceed the nominal wallthickness at ends remote from the associated open face (described below)in order for the vertical support members to maintain a desired draft.

In order to practically form hitch step 100 as an injection molded or areaction injection molded part, the structure has to have at least oneopen face to permit the molding of thin walls. In the embodimentsillustrated in FIGS. 1-4 and 16-18, there are three such open faces: anopen bottom 230, 250 which includes the entire bottom of the step body102 as well as the bottom of a tongue throat region 232, an open rightside 310 of a forward region 400 of the tongue 104 which extendsforwardly from throat region 232 and as seen in FIG. 3, and an open leftside 312 of tongue forward region 400 which is the mirror image of openright side 310. As shown in FIG. 3, the forward region 400 of the tongue104 is substantially hollow. Other embodiments may have more ordifferent open faces, some of which will be described below.

Each open face is an exterior boundary of the hitch step 100 and is aface of a mostly hollow cavity or volume. The volume extends from theopen face, preferably at 90 degrees thereto, upward, downward or inwarduntil it is terminated by an intervening panel, or until the oppositeexterior side of the hitch step is reached. The intervening panel can bedisposed somewhere in the middle of the part, in which case an opposedmolding gate will be necessary, or the intervening bounding panel can bethe same as an exterior panel of the hitch step on the other side. Wherethere is no intervening bounding panel, the volume will reach an opposedopen face, as is seen for example in the embodiments shown in FIGS. 8and 9. In many embodiments, the volumes of regions 102, 232 and/or 400are divided into cells by internal reinforcing or supporting members.

For the illustrated step body 102 of hitch step 100, the open face 230is a face of a volume which extends upwardly until the lower surface oftop external panel 116 is reached. In the embodiments illustrated inFIGS. 1-4 and 16-18, this volume is segmented into a plurality of opencells 248, each of which is approximately prismatic: a top of each cell248, as formed by top panel 116, has a shape and area similar to thebottom of the cell in the plane of the open bottom 230.

While the cells 248 are approximately and substantially prismatic, theyare not completely so. The surfaces of the internal walls 204, 206, 214preferably will have a draft, such as ½ degree, and as such thecross-sectional area of these cells 248 bounded by walls 204, 206, 214become smaller as one proceeds upward. The interior surfaces of exteriorpanels 106, 114, 210, 212 are formed to be in parallel with theirrespective exterior surfaces, and in this illustrated embodimenttherefore are disposed at a draft of 3 degrees.

The tongue 104 has a throat region 232 with a bottom open face 250, asseen in FIG. 2. In at least some mounting configurations the throatregion will at least partially protrude from the vehicle hitch receiver(not shown; see FIGS. 9 and 10) in a rear direction. Therefore, thethroat region 232 is most susceptible to cantilever bending from anon-axis load, and to torsion caused by a vertical load imposed on toppanel 116 at a location transversely displaced from axis X; the hitchstep 100 is more susceptible to bending and twisting here thanelsewhere, all other things being equal. To resist this torsion, a leftwall 234 and a right wall 236 of the throat region 232 can be made to beentire and to have a thickness which is the same as the chosen nominalwall thickness for the hitch step 100. Throat region 232 further mayhave a central vertical support plate or member 302 on axis X, which iscolinear with one of the longitudinal support members 214 in step body102, and which extends forwardly through forward region 400 of tongue104 (see FIG. 4). In the embodiment illustrated in FIGS. 2 and 4, thethroat region 232 further has one transversely oriented reinforcingmember or plate 238 which intersects longitudinal central support member302 and which extends between right exterior side wall 236 and leftexterior side wall 234. The thickness of walls 302 and 238 can beone-half of the nominal wall thickness of hitch step 100, or can beincreased to about 100% of the nominal wall thickness. To providefurther resistance to torque around axis X, further transversereinforcing members can be added in throat region 232, as will bedescribed in conjunction with FIGS. 14 and 16 below.

Among the longitudinally oriented support members 214 of the step body102 are a member 240, seen in FIG. 2 to be disposed a little to theright of tongue sidewall 236 (FIG. 2 being a bottom view), and a member242, disposed a little to the left of tongue sidewall 234. Further, arear, transverse support member 244 of throat region 232 has ends whichcurve forwardly before their respective junctions with front panel 212and throat region side wall 236 or 234. These junctions areintentionally offset or jogged from each other to more uniformlysolidify hitch step 100 during cooling and prevent a void from formingat what would otherwise be a thickened location formed from the junctionof multiple walls.

At its union with the front panel 212 of the step body 102, the entirecross-sectional area (height by width) of tongue 104 is contained withinthe area of the front surface of front panel 212. In this fashion, allof the external walls and the internal reinforcing plates of the throatregion 232 are available to resist any torsion caused by off-axis orcantilever loading of step body 102.

In the embodiment illustrated in FIGS. 1-4, the throat region 232 has anopen bottom or face 250 and is segmented into four somewhat prismaticcells 252. In this embodiment, the same mold core used to define theinternal structure of step body 102 is also used to define the internalstructure of throat region 232. The volume bounded by open face 250 endsat a lower surface of tongue top panel 120. The internal surfaces of thewalls forming the cells 252 have a draft which can be chosen to be ½degree.

As shown in FIGS. 1-4, the receiver tongue 104 is disposed around axisX, and in this illustrated embodiment has a top panel 120 and a bottompanel 218 (See FIG. 2) opposed to and spaced from the top panel 120. Thetop panel 120 and the bottom panel 218 are substantially parallel withthe axis X. A top surface of the top panel may have a concave groove orindentation 132 in parallel to axis X and extending for the length oftongue 104, while a longitudinally extending concave groove orindentation 222 in the bottom surface of tongue bottom panel 218 mayextend from the throat region 232 to a forward end 246 of the tongue 104(FIG. 2). A central, longitudinally extending reinforcing wall, panel orplate 302 (See FIGS. 3 and 4) may be vertical. Respective upper andlower ends of the wall 302 may be aligned with the top indentation 132and/or bottom indentation 222, to hide any mold marks.

In this embodiment, a plurality of cylinders 122 are disposed in thereceiver post body 104 at an angle to the axis X, such as 90 degrees. Auser-selected one of the cylinders 122 will receive a hitch pin of thehitch receiver, thereby attaching the hitch step 100 to the hitch.Accordingly, the number and placement of cylinders 122 may vary due tothe type of receiver-type hitch being used and the application. Each ofthe cylinders 122 extends through the center panel or plate 302 (seeFIGS. 3 and 4) between the open right and left sides 310, 312 of theforward region 400 of the tongue 104. Each cylinder 122 is formed by awall 314 whose thickness may be chosen to be the same as the nominalwall thickness of hitch step 100. In the embodiment illustrated in FIGS.1-4, the cylinder walls 314 intersect and overlap each other at ahorizontal plane including axis X, so that a longitudinal distancebetween the internal surface of any cylinder and that of an adjacentcylinder is about the same as the thickness of walls 314.

Each cylinder 122 may have a support structure which includes a topvertical member 124 in parallel with a center of the cylinder 122 andextending from the cylinder 122 to the top panel 120, and a bottomvertical member 126 in parallel with the center of the cylinder 122 andextending from the cylinder 122 to the bottom vertical member 218.Vertical members 124, 126 may have thicknesses which are many timessmaller than their lengths and may be plates or panels, as shown, andmay have thicknesses specified as the nominal wall thickness or afraction thereof. Support panels 124, 126 are oriented transversely fromaxis X. The support structures 124, 126 support cylinders 122 butprovide limited resistance to a rear axially applied impact force; inthis illustrated embodiment, all of the impact force (to the extent notalready absorbed by step body 102) has to be absorbed by cylinders 122,top panel 120, bottom panel 218 and central panel 302.

Cylinders 122 are disposed in a forward region 400 of the tongue 104which extends forwardly from throat region 232 to forward end 246. Inthis embodiment, region 400 has two opposed open exterior faces 310, 312(FIG. 2) that are vertically disposed. Two side actions of the mold areused to mold region 400, and these meet to define a portion of thelongitudinal reinforcing member 302. Forward region thus has two opposedopen faces respectively defining two forward region volumes, each ofwhich are terminated by central wall or panel 302. The wall surfacesextending inwardly from open faces 310, 312 can have drafts chosen as ½degree.

As seen in the sectional view of FIG. 4, not all of the support membersin step body 102 have to extend for the entire height of the step body102. In this embodiment the oblique members 208 are not as tall as thestep body's external panels or other supporting members. In alternativeembodiments, the height of the internal vertical support members candecrease as a function of their distance from axis X (see FIG. 12).

In the embodiment shown in FIGS. 5 and 6, a hitch step indicatedgenerally at 500 has a step body 102 which is integrally injectionmolded with a tongue member 104, as before. However, to increase theresistance to torsion in throat region 502, a reinforcing member 504 hasbeen added. Reinforcing member can be made of a metal such as steel, andit is preferred that reinforcing member 504 be made of a metal, such ashigh-carbon steel, that tends more to elasticity than malleability.Reinforcement 504 is vertically disposed along axis X and extends from arear end 506 that is within step body 102, to a forward end 508 that iswell forward of the throat region 502. The forward end 508 can beslotted, as shown, so that any force tending to forwardly displace thereinforcement or insert 504 within the hitch step 100 will not result inthe occlusion of the rearwardmost cylinder 122. A central longitudinalreinforcing member is in this embodiment divided into right and leftwalls 510, 512, which, in the instance that member 504 is made of steel,will protect member 504 from corrosion. While reinforcement 504 has beenadded, the hitch step 500 is otherwise completely injection-molded of athermoplastic polymer compound.

A hitch step according to the invention may otherwise use two pieces,assembled together. For example, a tongue could be formed of steel oraluminum and the step body from an impact plastic; the step body wouldbe bolted onto the tongue. Alternatively, the tongue and the step bodyare different grades of injection molded plastic, in which a compoundfor the tongue is chosen for strength, while another compound is chosenfor impact resistance. These separate components could be assembled in anumber of ways, such as bolts, screws, adhesives or matingsnap-features.

FIG. 7 is a bottom view illustrating a hitch step 700 in which allinternal support members have been omitted from step body 702. Tongue104 can be formed as described for FIGS. 1-4 or FIGS. 5-6. The step body702 continues to have a rearward exterior panel 106, a front exteriorpanel 212, a right exterior panel 114, a left exterior panel 210 and atop panel 116. The thicknesses of panels 106, 212, 114 and 210 may beincreased, as they are the only support members and will provide thesole resistance to a vertical load on the top panel 116 of the hitchstep 700. Depending on the thicknesses and polymer compound selected,the resistance to torsional force may still be the most critical at thethroat region 706; while longitudinal and transverse internal supportmembers 708, 710 may be needed in the throat region 706, such internalsupport members at more of a distance from axis X can either be reducedor, as here, entirely omitted. Nonetheless, hitch step 700 is moldable,as by injection molding, reaction injection molding or compressionmolding, from a thermoplastic or thermosetting polymer compound, as itcontinues to have at least one open face for all regions of the step700, and continues to be formed as a substantially hollow structure withrelatively thin walls.

FIG. 8 illustrates an embodiment that is the logical reverse of theembodiment shown in FIG. 7. A hitch step 800 has a tongue member 104that is constructed much as the other tongue members described in FIG.1-4 or 5-6. However, the hitch step body 802, which continues to beintegrally molded with tongue 104 from a thermoplastic polymer compound,has no external panels at all, but only internal reinforcing members.These include a plurality of transversely extending, parallel,spaced-apart, vertical walls or support members 804, with whichintersect a plurality of longitudinally extending, parallel,spaced-apart, vertical walls or support members 806. A vertical loadsurface (for the foot of a user) is formed by upper surfaces 808 of themembers 804, 806. Hitch step 800 has multiple open faces and relativelythin walls which make it conducive to fabrication by injection molding.The intersections of support members 804 and 806 form a matrix ofsubstantially prismatic cells, and together present a step or topsurface to the user. At the same, time, support members 804 and 806 forma volume which can compress during a rear impact, thereby absorbingenergy that otherwise would be transmitted to the rest of the vehicle.Other embodiments can be molded which are structurally intermediate theembodiments shown in FIGS. 7 and 8; a designer can decide to omit one ormore exterior panels or sections of same, or add or subtract variousinternal reinforcing members from the step body as desired resistance totorsion around axis X dictates.

In the embodiments illustrated in FIGS. 1-8, the hitch step body hasbeen formed by exterior and/or interior panels or walls which aresubstantially planar. But this does not have to be the case. The hitchstep body should have at least one external or internal verticallydisposed support member to resist a vertical load as would be imposed bya foot of a user, should somehow define an upper surface upon which theuser can step, should be formed by walls to a nominal wall thicknessstandard, and should have at least one open face through which a moldcore can operate. But the vertical support walls can take various curvedor even irregular shapes and still meet all of these criteria.

Once such exemplary embodiment is shown in FIG. 9. A hitch stepindicated generally at 900 is molded from a polymer compound, and has astep body 902 which is integrally molded with a tongue or tang 904. Butthe step body 902 is formed by a series of intersecting, verticallydisposed cylinders 906 formed by cylinder walls 908. The cylinder walls908 have a substantially uniform thickness that can be chosen to be thesame as the nominal wall thickness preselected for the hitch step 900;they can also have surfaces with small of amounts of draft from themolding surface and inwardly, such that the thickness of the cylinderwalls 908 decreases from top to bottom, or vice versa. Upper ends 910 ofthe cylinder walls 908 are selected to occupy the same horizontal plane,thereby presenting a surface upon which a user can step. Each portion ofa cylinder wall 908, other than a portion which is precisely parallel toaxis X, will offer some resistance to torsion around axis X as might becaused by weight imposed at exemplary off-axis location 912. The hitchstep body 902 is divided into a series of tubular cells, and its volumeis bounded by both top and bottom open faces.

In this embodiment, a throat region 914 of the tongue 904 is formed by aleft side wall 916, a right side wall 918, and a central longitudinalmember 920 which extends for the entire length of the tongue 904. Walls916, 918 and 920 are intersected by transverse members 922, 924 and 926.All of walls 916-926 are oriented to be vertical. Both the top and thebottom of the throat region are open and this embodiment does not employany intervening panel which would bound a volume extending inwardly fromeither open face.

A forward region 930 of the tongue 904 is formed as an open latticewithout exterior side, top or bottom walls. Unlike a trailer tang ortongue that normally is received in a trailer hitch receiver, the tongue904 will experience little tensile force along axis X, and therefore thestructure of tongue 904 can be less substantial. A plurality oftransverse members 932, 934, 936 extend vertically and horizontally fromaxis X to form squares which slidably fit within the receiver for whichthe hitch step 900 is intended; they can be 1.9 inches in height andwidth, for example. One or a series of hitch pin holes (not shown) areformed through central plate 920 to intersect axis X, so that a trailerhitch pin may be received in one of them.

As so constituted, hitch step 900 can be injection-molded from athermoplastic polymer compound. All of its walls can be fabricated to anominal wall thickness or a predetermined fraction thereof, and arerelatively thin as compared with the overall dimensions of the hitchstep 900, and multiple open external faces present themselves forinsertion of mold cores. The transverse members 932, 934, 936 divide theforward region into several cells. Right and left volumes of the forwardregion extend inwardly from the open faces until they terminate atcentral longitudinal member 920.

FIG. 10 is an illustration of how one embodiment of the hitch stepdeflects when subjected to an off-axis rear impact. In this example, ahitch step 100 substantially as described in FIGS. 1-4 isinjection-molded of Hytrel® 7246. Hitch step 100 is slid into a hitchreceiver 1000 and fastened in place with the aid of a hitch pin 1002.The hitch receiver 1000 had been installed on a pickup truck having aweight of about 4000 pounds. The truck was backed into a stationaryobject (in particular, a vertical cylinder) at about 1-2 mph such thatthe object impacted the hitch step 100 at the point indicated at thearrow 1004.

In response to this off-axis impact, the hitch step twisted in ahorizontal plane, so that the left exterior panel 210 was displacedforward, and the right exterior panel 114 was displaced rearward. Thehitch step 100 basically twisted in that portion of the throat region232 that was disposed rearward of the receiver 1000. Less dramatic andmore local compression and distortion of step body members 106, 212,208, 214, 216 was also seen. After the truck was driven forward afterimpact, the hitch step returned to its pre-impact location with perfectelastic memory.

FIG. 11 illustrates an embodiment in which a hitch step 1100 isinjection-molded in a two-shot process. A hitch step body 1102, throatregion 232 and forward tongue region 400 can be injection-molded of arelatively tough and stiff thermoplastic polymer compound, as describedpreviously, and otherwise having the structural characteristics of theembodiment illustrated in FIGS. 1-4. Once completed, a friction pad 1104can be overmolded onto an upper surface 1116 of the hitch step body1102. The polymer for the second-shot injection can be chosen to have amore frictional surface than would be obtained from the first-shotpolymer; for example, a relatively soft TPE could be selected. A topsurface of the friction pad 1104 can have longitudinal and transverseelongate concave treads 1106, 1108, similar in form to treads 128, 130seen in FIGS. 1-4. Other tread surfaces can be chosen instead astraction and ornamental characteristics dictate, as these are no longeraffected by the presence of molded support members underneath them.

According to one aspect of the invention, a height of the hitch stepbody is selected to house internal or external support members thatpresent sufficient y-z cross sectional area (y being transverse and zbeing vertical) that torsion around axis X can be adequately resisted.FIG. 12 illustrates that this height does not have to be uniform. Ahitch step indicated generally at 1200 has a step body 1202 that ingeneral is formed like body 102 of hitch step 100, as seen in FIGS. 1-4.But a rear external side wall 1204 of step body 1202 has a maximumheight through a transverse segment near axis X, and then transverselytapers. The tapering can be linear, as shown. A height of a rightexterior side panel 1206 and that of a left exterior side panel 1208 canbe chosen to be significantly less than the maximum height of rear panel1204. This is because as the transverse distance from axis X grows, theresistance to torque around axis X provided by any support memberlocated at that transverse distance need not be as great. The height ofany and all internal support members (not shown) can be reduced insimilar fashion. A height of a forward external panel (not shown) ofstep body 1202 can generally conform to the shape of the rear panel1204.

A tongue 1210 can have a throat region 232 similar to that described forhitch step 100 (FIGS. 1-4). A forward region 1212 of the tongue 1210extends axially forwardly from throat region 232. The forward region1212 has a top panel 1214 and an exterior right wall 1216 that extendsdownwardly from top panel 1214 to a bottom panel 1218. Two hitch pincylinders 1220, 1222 open onto the surface of right wall 1216. Unlikethe embodiment shown in FIGS. 1-4, the cylinders 1220, 1222 are spacedapart from each other. It is also possible to have only a single hitchpin location.

As seen in FIG. 13's top sectional view, the forward region 1212 has noaxial vertical longitudinal member; this has been moved rightward toform right side wall 1216. The left side of the forward region 1212 hasan open external face 1224 that bounds a volume which extends to theinner surface of right exterior panel 1216. A cylinder sidewall 1226forms cylinder 1220 and a further cylindrical sidewall 1228 formscylinder 1222, and these extend from the open face 1224 to the righttongue side wall 1216. A transverse vertical member 1230 upwardlyextends from cylindrical sidewall 1226 to top panel 1214 (FIG. 12). Aparallel transverse vertical member 1232 upwardly extends fromcylindrical sidewall 1228 to top panel 1214. Similar transverse verticalmembers are positioned below the cylindrical sidewalls 1226, 1228 toextend to bottom panel 1218, as per the embodiment shown in FIGS. 1-4.Horizontal panel 1234 extends rearwardly from cylindrical sidewall 1226.Horizontal panel 1236 spans the axial distance between cylindricalsidewalls 1226 and 1228. Horizontal panel 1238 extends betweencylindrical sidewall 1228 and a forward wall 1240. All of the horizontalpanels 1234, 1236, 1238 reside in the plane including axis X. All of thewalls 1240, 1238, 1228, 1232, 1236, 1230, 1226 and 1234 extend inwardlyfrom the open face 1224 to terminate at wall 1216, and thus forwardregion 1212 is a single volume which can be formed by a single sideaction. The walls 1240, 1238, 1228, 1232, 1236, 1230, 1226 and 1234 canall have a slight draft from open face 1224 to closed right wall 1216,so that the cells which they form are larger at open face 1224 than theyare at wall 1216.

In the embodiment shown from the bottom in FIG. 14, a hitch stepindicated generally at 1400 is molded of a polymer compound as describedfor FIGS. 1-4 and in general has the same structural characteristics.However, in a throat region 1402, diagonal support members or ribs 1404,1406 have been added for stiffness. The throat region 1402 is rearwardlybounded by a transverse support member 1408. A second transverse supportmember 1410 is positioned orthogonally to axis X and in parallel tosupport member 1408, to span between right external panel 1411 and leftexternal panel 1412. A central longitudinal vertical member 1414 extendsalong axis X all of the way through a tongue 1416 of the hitch step 1400and through most of a hitch step body 1418. Diagonal member 1404 extendsfrom a junction of transverse member 1410 and longitudinal member 1414,rearwardly and rightwardly to near a junction of member 1408 and wall1411. In bilateral symmetry, diagonal member 1406 extends from ajunction of transverse member 1410 and longitudinal member 1414,rearwardly and leftwardly to near a junction of member 1408 and externalside panel 1412 of tongue 1416.

A third diagonal rib or support member 1424 proceeds from near ajunction of right external side panel 1411 and external forward panel1426 of the step body 1418, rearwardly and leftwardly to near a junctionof a transverse support member 1428 of body 1418 and centrallongitudinal member 1414. A fourth diagonal rib or support member 1430proceeds from near a junction of left external side panel 1412 andforward external side panel 1426 of the step body 1418, rearwardly andrightwardly to near a junction of transverse support member 1428 andcentral longitudinal member 1414. The addition of diagonal members 1404,1406, 1424, 1430 divide cells which substantially had beenparallelogram-based prisms into cells which substantially are triangularprisms. The four sided prisms had a freedom to deform, in which sides inparallel to each other could be deflected to be farther apart or closerto each other, while the three-sided prisms do not possess this freedomof motion.

The thicknesses of selected ones of the internal support members of thestep body 1418 have been increased to provide further resistance totorsion around axis X, and further resistance to bending in a verticalplane including axis X. The thickened members include centrallongitudinal member 1414, a longitudinal member 1420 to the right of itand slightly to the right of external sidewall 1411, and a longitudinalmember 1422 to the left of central member 1414 and slightly to the leftof left external sidewall 1412. Transverse members 1428, 1432 and 1434are make thicker not through their entire lengths but only for sectionsrelatively near axis X.

In FIG. 15, a hitch step indicated generally at 1500 includes a hitchstep body 102, a throat region 232 and a forward tongue region 400,integrally molded from a polymer compound, and similar in structure tothe embodiment shown in FIGS. 1-4. But the hitch step 1500 also includesa separate insert 1502 which is meant to fill selected ones of the cellsformed in the throat region 232 and the body 102. These cells includecells 252 of the throat region 232. The filled cells further includecell 1504, bounded by front body panel 212, longitudinal support member1505, internal transverse member 204 and longitudinal support member240; cell 1506, bounded by longitudinal support member 240, transversemember 244, central longitudinal member 214, and transverse member 204;cell 1508, bounded by central longitudinal member 214, transverse member244, transverse member 204 and longitudinal member 242; and cell 1510,bounded by longitudinal member 242, front body panel 212, longitudinalmember 1512 and transverse member 204. The insert 1502 has fillingportions 1514 that are dimensioned to be closely received intorespective ones of the cells 252, 1504, 1506, 1508 and 1510, as bysnap-fitting, press-fitting and/or the use of an adhesive. As inserted,the filling portions 1514 will greatly increase the resistance to torquearound axis X of the throat region 232 and adjacent region of step body102. The insert 1502 could also be second-shot injection molded.

In FIG. 16, a hitch step indicated generally at 1600 is molded of apolymer compound as described for FIGS. 1-4 and in general has the samestructural characteristics. However, in a throat region 1602, diagonalsupport members or ribs 1604, 1606, 1608 and 1610 have been added forstiffness. The throat region 1602 is rearwardly bounded by a transversesupport member 1612. A second transverse support member 1614 ispositioned orthogonally to axis X and in parallel to support member1612, to span between right external panel 1616 and left external panel1618. A central longitudinal vertical member 1620 extends along axis Xall of the way through a tongue 1622 of the hitch step 1600 and throughmost of a hitch step body 1624. Diagonal member 1604 extends from ajunction of transverse member 1614 and longitudinal member 1620,rearwardly and rightwardly (leftwardly in this bottom view) to near ajunction of member 1612 and wall 1616. In bilateral symmetry, diagonalmember 1606 extends from a junction of transverse member 1614 andlongitudinal member 1620 rearwardly and leftwardly to near a junction ofmember 1612 and external side panel 1618 of tongue 1622. Diagonal member1608 extends from a junction of transverse member 1614 and longitudinalmember 1620, forwardly and leftwardly to the junction of external sidepanel 1618 and transverse member 1626. Diagonal member 1610 extends froma junction of transverse member 1614 and longitudinal member 1620,forwardly and rightwardly to the junction of external side panel 1616and transverse member 1626.

Four additional diagonal ribs or support members 1630, 1632, 1634, and1636 are rearward of member 1612. Diagonal member 1630 proceeds fromnear a junction of right external side panel 1616 and external forwardpanel 1638 of the step body 1624 rearwardly and leftwardly to near ajunction of a transverse support member 1640 of body 1624 and centrallongitudinal member 1620. Diagonal rib or support member 1632 proceedsfrom near a junction of left external side panel 1618 and forwardexternal side panel 1638 of the step body 1624 rearwardly andrightwardly to near a junction of transverse support member 1640 andcentral longitudinal member 1620. Diagonal rib or support member 1634proceeds from near a junction of transverse support member 1640 andlongitudinal member 1620 forwardly and leftwardly to near a junction oftransverse support member 1642 and longitudinal member 1648. Diagonalrib or support member 1636 proceeds from near a junction of transversesupport member 1640 and longitudinal member 1620 rightwardly andforwardly to near a junction of transverse support member 1642 andlongitudinal member 1646. The addition of diagonal members 1630, 1632,1634, and 1636 divide cells which had been parallelogram-based prismsinto cells substantially like triangular prisms. The four sided prismshad a freedom to deform, in which sides in parallel to each other couldbe deflected to be farther apart or closer to each other, while thethree-sided prisms do not possess this freedom of motion.

Selected ones of the internal support members of the step body 1624 havebeen increased in thickness to provide further resistance to torsionaround axis X. The thickened members include central longitudinal member1620, a longitudinal member 1646 to the right of it and slightly to theright of external sidewall 1616 and a longitudinal member 1648 to theleft of central member 1620 and slightly to the left of left externalsidewall 1618. Transverse members 1640, 1642 and 1644 are make thickernot through their entire lengths but only for sections relatively nearaxis X. The thickened members can be about 50% or 0.1 inches thickerthan the other internal structural members for example, and approach thenominal wall thickness used to design the hitch step.

In FIGS. 17 and 18 the receiver post body 1700 generally has the samecharacteristics as the receiver post body 104 shown in FIG. 3. In thisembodiment, a plurality of cylinders 1702 a-e are disposed in thereceiver post body or tongue 1700 at an angle to the axis X, such as 90degrees. Each cylinder 1702 a-e may have a support structure whichincludes a top vertical member 1704 in parallel with a center of thecylinder and extending from the cylinder to the top panel 1706. Theremay also be bottom vertical members 1708 underneath respective ones ofthe cylinders 1702 a-e, and in parallel with their respective centers,and each extending from a respective cylinder to the bottom panel 1710.There may also be v-shaped diagonal members 1712 a-d extending from theadjacent cylinders 1702 a-e to the top panel. For example, v-shapedmember 1712 a has legs which extend from cylinders 1702 a and 1702 b tothe top member 1706. Likewise, there may be v-shaped diagonal members1714 a-d extending from adjacent cylinders to the bottom panel 1710. Forexample, legs of v-shaped member 1714 a extend from respective ones ofcylinders 1702 a and 1702 b to bottom member 1710. V-shaped members 1712a-d, 1714 a-d may have thicknesses which are many times smaller thantheir lengths and may be plates or panels as shown. The V-shaped membersprovide additional resistance to downward deflection when tongue 1700 isonly partly inserted into a hitch receiver, as by aligning forwardmostcylinder 1702 e with the hitch pin hole (not shown) rather than usingcylinder 1702 a.

The hitch step 100 resists torque in a transverse vertical plane whenweight is placed on the top surface of the step body 102. For example,for the embodiment shown in FIG. 16, as fabricated from DuPont Hytrel®7246 to a nominal wall thickness of 0.2 inches, if at room temperature a250 pound person steps on a portion of the top surface of step body 102at a distance from axis X of approximately four inches, the top surfaceof the step body 102 should deflect in a transverse vertical plane (thatis, one orthogonal to axis X) by no more than about ten degrees from thehorizontal plane that the top surface occupies at rest or in an unloadedcondition. Preferably, a 200 pound person stepping on this location, atroom temperature, will cause a deflection in the transverse verticalplane of no more than about six degrees, and a 300 pound person steppingon this location, at room temperature, will cause a deflection in thetransverse vertical plane of no more than about eight degrees. Theplacement, thickness and composition of the hitch step 100's reinforcingmembers are provided to minimize the amount of vertical deflection whenstep 100 is being used as a step, while at the same time permitting adegree of elastic horizontal compression when it is acting as a bumper.

In summary, several embodiments of a hitch step have been described, allof which can be molded from a polymer compound. The hitch steps aresubstantially hollow, having plural open exterior faces to permit theirfabrication by molding, and are constituted by walls and reinforcingplates which are many times thinner than the overall dimensions of thehitch steps. The hitch steps are capable of supporting the weight of atypical user, while also absorbing energy from rear impact. Whileillustrated embodiments of the present invention have been described andillustrated in the appended drawings, the present invention is notlimited thereto but only by the scope and spirit of the appended claims.

We claim:
 1. A hitch step for insertion into a hollow vehicle hitchreceiver, the hitch step comprising: a substantially hollow step bodyhaving a height, a width transverse to an axis of the vehicle hitchreceiver and a depth in parallel to the axis, at least one transversesupport member inside the step body having a thickness that is manytimes less that the depth of the step body, the transverse membertransversely extending for at least a substantial portion of the stepbody and extending in a vertical direction for at least a substantialportion of the height of the step body, at least one external face ofthe step body in parallel to the axis being open; a substantially hollowtongue having a rear end joined to the step body and a front end axiallydisplaced from the rear end, the tongue sized to be slidably receivedinto the vehicle hitch receiver and in use providing the sole supportfor the step body, the tongue having a height and a width transverse tothe axis, the width of the tongue being many times less than the widthof the step body; a throat region of the tongue adjoining the step bodyand extending forwardly from the step body along the axis, at least oneexternal face of the throat region being in parallel to the axis andbeing open, a plurality of vertically disposed reinforcing plates of thethroat region extending from the open face to either a horizontal panelor to an opposed external face of the throat region; and a forwardregion of the tongue extending forwardly from the throat region of thetongue, the forward region having at least one external face parallel tothe axis which is open and a vertical plate disposed in parallel to theaxis, the vertical plate having a thickness in a transverse directionthat is many times less than the width of the tongue, a height of thevertical plate extending for at least a substantial portion of theheight of the tongue, at least one trailer hitch pin hole formed totransversely extend through the vertical plate; wherein the step bodyand the tongue are integrally molded of a thermoplastic elastomer. 2.The hitch step of claim 1, wherein the step body has a plurality oftransverse members including said at least one transverse member, thetransverse members being axially spaced apart from each other by adistance at least as great as the thickness of the transverse members.3. The hitch step of claim 1, wherein the step body has a top paneljoined to said at least one transverse member and extendingsubstantially for the entire width and depth of the step body, athickness of the top panel in the vertical direction being many timesless than the height of the step body.
 4. The hitch step of claim 1,wherein the vertical plate of the forward region of the tongue ispositioned on the axis and axially rearwardly extends through the throatregion and into the step body for a substantial portion of the depth ofthe step body.
 5. The hitch step of claim 1, wherein said at least onetransverse support member of the step body is one of a plurality ofinternal support members.
 6. The hitch step of claim 5, wherein ones ofthe internal support members intersect each other and divide the volumeof the step body into a plurality of cells.
 7. The hitch step of claim6, wherein the cells are substantially prismatic.
 8. The hitch step ofclaim 1, wherein the polymeric material is a polyester-polyethercopolymer.
 9. The hitch step of claim 1, wherein the thermoplasticelastomer exhibits a flexural modulus, as tested according to ISO 178,of at least 550 MPa at 23 C.
 10. The hitch step of claim 1, wherein whenthe tongue of the hitch step is inserted into a hitch receiver and a 250pound load is placed on a top surface of the step body at a locationtransversely displaced from the axis by 4 inches, the step body willdeflect in a transverse vertical plane by no more than ten degrees. 11.The hitch step of claim 10, wherein when the tongue of the hitch step isinserted into a hitch receiver and a 265 pound load is placed on a topsurface of the step body at a location transversely displaced from theaxis by 4 inches, the step body will deflect in a transverse verticalplane by no more than eight degrees.
 12. A hitch step for insertion intoa hollow vehicle hitch receiver, the hitch step comprising: a step bodyhaving a top surface substantially in a horizontal plane at rest, thestep body having a height, a width transverse to an axis of the vehiclehitch receiver, and a depth in parallel to the axis; a tongue having arear end joined to the step body and a front end axially displaced fromthe rear end, the tongue sized to be slidably received into the vehiclehitch receiver and in use providing the sole support for the step body,the tongue having a height and a width transverse to the axis, the widthof the tongue being many times less than the width of the step body, thetongue and the step body being integrally injection molded of athermoplastic elastomer; and wherein, at room temperature, and in atransverse vertical plane, the top surface of the step body deflects nomore than about ten degrees from the horizontal plane when a weight of250 pounds is placed on the top surface of the step body approximatelyfour inches from the axis, the step body being restored to its originalposition when the weight is removed.
 13. The hitch step of claim 12,wherein, at room temperature, and in a transverse vertical plane, thetop surface of the step body deflects no more than approximately eightdegrees from the horizontal plane when a weight of 300 pounds is placedon the top surface of the step body approximately four inches from theaxis.